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Scalar product used for length?

  1. Oct 20, 2013 #1
    I got asked how the scalar product can be used to find the length of a vector? Could someone please explain
     
  2. jcsd
  3. Oct 20, 2013 #2

    UltrafastPED

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    Do you mean vector product, also called the dot product?

    V°V = |V|^2.

    Or do you mean the triple scalar product:

    |A°BxC|= volume of the parallelepiped with three sides defined by A,B,C.


    If it is the triple scalar product you will need more information to obtain a vectors length - but the dot product provides it immediately.
     
  4. Oct 21, 2013 #3

    FeDeX_LaTeX

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    To my knowledge, the vector product and the dot product are never given the same meaning. The vector product yields a vector quantity; the dot product yields a scalar quantity.

    I'm not sure how one could use the scalar product to find the length of an arbitrary vector -- it seems like a redundant question to me. Do you know how to find the magnitude of a vector?
     
  5. Oct 21, 2013 #4

    UltrafastPED

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    There are many vector products: http://mathworld.wolfram.com/VectorMultiplication.html

    Two of those listed above result in a scalar. I was trying to determine which one he was referring to; the OPs language was ambiguous.

    The vector inner product (dot product) is the obvious method.

    But the original requestor has disappeared ... so the problem is dead.
     
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